Transmitter and receiver for electromagnetic waves



June 116 max WEYRICH 2,044,413

TR ANSNITTER AND RECEIVER FOR ELECTROMAGNETIC WAVES Filed Aug. 5; 1951 2Sheets-Sheet 1 c-wA'vEs June 16, 1936. R. WEYRICH TRANSMITTERQNDRECEIVER FOR ELECTROMAGNETI Filed Aug. 5, 1931 2 Sheets-Sheet 2 I N VENTO R:

Patented June 16, 1936 UNITED STATES TRANSMITTER AND RECEIVER FOBEIEGTROMAGNETIC WAVES Rudolf Weyrich, Brunn, Czechoslovakia ApplicationAugust 5. 1931. Serial No. 555,386 In Germany August I, 1930 11 Claims-(Cl. 250-11) It is a known fact in acoustics that the action of a sourceof sound can be substantially improved by the co-operation of aresonance space and that also the efiect of sound waves which are 5received is increased by the use of resonating spaces. In transmittingor receiving electromagnetic waves use has only been made of deviceswhich are capable of resonating to the extent of using transmitting andreceiving circuits with the 10 corresponding aerials, that is, wiresystems which are capable of resonating down to the same frequency. Itis, however, possible by using spaces which are capable of resonating,which are filled with any semi-conductor or non-conductor pref- 15erably with the medium through which the transmission takes place, toobtain similar effects to those known in acoustics. For this purpose itis necessary that these spaces, which must be connected with the outerspace, should be limited by surfaces which have different electrical andmagnetic constants from the enclosed medium. Preferably these surfaceshave a much greater conductivity.

The invention therefore consists in an apparatus for transmitting andreceiving electromagnetic waves in which spaces capable of resonatingare provided in the immediate surroundings of an apparatus for emittingor absorbing electromagnetic waves which are surrounded by limiting asurfaces of suitable material which may consist of compact metal, a wirefabric or other suitable arrangement of wires or in general of amaterial which differs from the enclosed medium in its electromagneticproperties. These surfaces must have such geometric shape that the spaceenclosed has fundamental frequencies which can be excited in resonanceby an electromagnetic excitation of the same frequency. The existence ofsuch fundamental frequencies can be discov- .0 ered by obtainingexperimentally a resonance curve which shows the amplitudes of theelectric vector in the enclosed space as a function of the excitingfrequency. Fundamental frequencies are indicated by maxima on thiscurve. As these 5 maxima are never very sharp the desired action alsotakes place near to a fundamental frequency so that exact resonance isnot always necessary to obtain the effect.

On account of spaces capable of resonating being enclosed the inventiondiffers characteristically from other inventions in which conductingsurfaces are arranged near to a transmitting or receiving apparatuswhich, however, only act as reflectors and are intended to produce adirecting effect on the electromagnetic radiation. These known apparatusdepend chiefly on the geometrical-optical focusing properties ofsurfaces of the second order, as for example, parabolic or ellipticalcylindrical reflectors. It has been found of advantage to combine theaction of spaces which are capable of resonating with the action of suchreflectors where it is technically possible.

Fig. 1 is a diagrammatic view of a pair of planes between which anelectrical receiver or aerial is placed,

Fig. 1a is a similar view of a modified form in which means are providedfor adjusting the planes relative to one another,

Fig. 2 is a diagrammatic perspective view illustrating reflectingsurfaces in the form of a square, r

Fig. 2a is a perspective view of a modified form of arrangement shown inFig. 2 showing another meansfor adjusting the planes,

Fig. '3 is a diagrammatic perspective view of a cylindrical reflectingsurface for enclosing the aerial, and

Fig. 3a is a perspective view of the modified form of the arrangementshown in Fig. 3.

The simplest geometrical configuration of boundary surfaces whichenclose a space which can resonate, consists of a pair of parallelplanes between which an electromagnetic transmitter or receiver isplaced. Such an arrangement is illustrated diagrammatically in Figure 1,in which E1 and E2 indicate the two boundary planes and A is an aerial.If E1 and E: are taken as extending indefinitely and completelyconducting there is resonance for the Hertz function of the radiationfield, if the distance between the planes is an integral multiple of ahalf wave length in the intervening medium.

When the conductivity is not perfect and the extension of the planes isfinite there are corresponding alterations. The surface of the earth maywith advantage be used as the plane E2 in which case when necessary forincreasing the effect in the immediate surroundings of A itsconductivity is to be increased by suitable measures. Furthermore it isof advantage to make the distance the planes E1 and E2 variable so thatwhen the frequency is changed the apparatus can be adjusted. As is shownin Figure 2, it is possible by providing the sides with one or moreabsorbing or reflecting surfaces F to prevent radiation entering orpassing out in undesired directions in which case the reflectingsurfaces may be so shaped that they concentrate the radiation in givendirections.

These surfaces may also be provided for increasing the capability ofresonating of the space between E1 and E2 which is desirable becausewith this configuration in the case of infinitely extended perfectlyconducting planes there is resonance actually only for the Hertzfunction of the radiation field and not for the electric and a magneticfield strengths. In spite of the incompleteness of the resonance in thiscase, this arrangement is noteworthy because, by producing an infinitenumber of mirror images of the aerial by means of E1 and E3 the effectof an infinitely extended aerial system is obtained. Substantiallybetter resonance effectswhich apply not only to the Hertz function butalso to the field strengths are obtained by enclosing the aerial in aprismatic o'r cylindrical resonance space with a polygonal or curvedcross-section. The cylindrical surface C for enclosing the aerial A asshown in Figure 3, may preferably be closed by a further reflecting orabsorbing surface F or the cylinder may be closed on both sides and bein communication with the exterior only through a window. If C is takenas a perfectly conducting circular cylinder the resonance frequencieshave a simple relation to the zero values of the Bessel function Jo.

If r is the radius of the cylinder, 0 the velocity of light, to theangular frequency of the electromagnetic oscillations that is, thenumber of oscillations in 27r seconds, k1 one of the zero values of theBessel function Jo, e the dielectric constant, and a the permeability ofthe medium enclosed by the cylinder, in the case of resonance thefollowing relation holds:

It must be pointed out that the spaces capable of resonating may beproduced in many other manners, that the boundary surfaces may bespherical, ellipsoidal or of any other shape pro vided the spaceenclosed by them has fundamental electromagnetic frequencies andfurther, that the aerial need not necessarily lie within these spacesand that any kind of transmitting or receiving apparatus can be used.The arrangements described fully above are to be regarded only asspecial examples employed for explaining the invention. In general also,it is possible to tune the apparatus exactly to resonance or to dispensewith sharp resonance, to make the apparatus regulable by making theboundary surfaces adjustable, to obtain special screening or directionaleffects by providing additional reflecting or absorbing surfaces and tomake use of the surface of the earth as a boundary surface.

Figs. 1a, 2a and 3a show constructional examples of resonance spaceswith adjustable boundary surfaces. In Fig. 1a the distance between thetwo plates is altered by means of pulley blocks R'. In Fig. 2a the plateE1 is guided in slots S in the side surface F by means of clampingscrews K. In Fig. 3a the cylindrical surface C is adjusted by varyingthe overlap of the ends and securing by means of the clamping screws L.

What I claim is:

1. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with reflectors near to the antenna, thereflectors enclosing a space having a natural frequency approximatelycoinciding with the frequency of the electromagnetic waves.

2. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with two plane parallel reflectors, one oneach side of the antenna, the distance between the reflectors beingapproximately an integral multiple of the half wave length of theelectromagnetic waves.

3. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with a cylindrical reflector surrounding theantenna, a-natural frequency of the space enclosed by the cylindricalreflector being approximately equal to the frequency of the electromagnetic waves.

4. In apparatus for signaling by means of elec tromagnetic waves, thecombination of an an tenna with a cylindrical reflector surrounding thlantenna, the dimensions of the reflector agreeing with the formula Ho e1T ck? where r is the radius of the cylinder, c the velocity of light,to the angular frequency of the electromagnetic oscillations, IC'r oneof the zero values of the Bessel function Jo, and E the dielectricconstant and ,u. the permeability of the medium enclosed by thecylindrical reflector.

5. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with a prismatic reflector surrounding theantenna, a natural frequency of the prismatic space enclosed by thereflector being approximately equal to the frequency of theelectromagnetic oscillations.

6. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with reflectors near to the antenna, thereflectors enclosing a space of which a natural frequency isapproximately equal to the frequency of the electromagnetic oscillationsand with screening surfaces adapted to prevent radiation in certaindirections.

7. In apparatus for signaling by means of electromagnetic Waves, thecombination of an antenna with two plane parallel reflectors on bothsides of the antenna, the distance between the reflectors beingapproximately an integral multiple of the half wave length of theelectromagnetic waves and means for adjusting the distance be tween thereflectors so that it can be adapted to different wave lengths.

8. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with a plane reflector parallel to the surfaceof the earth and disposed above the antenna, the distance of thereflector from the surface of the earth being approximately an integralmultiple of the half wave length of the electromagnetic waves.

9. In apparatus for signaling by means of electromagnetic waves, thecombination of an antenna with reflectors near to the antenna, whichreflectors, together with the surface of the earth, enclose a space ofwhich the natural frequency is approximately equal to the frequency ofthe electromagnetic oscillations.

10. A combination of an antenna with reflectors near to the antenna,which reflectors, together with the surface of the earth, enclose aspace of which a natural frequency is approximately equal to thefrequency of the electromagnetic oscillations and with conductingsurfaces which are adapted to prevent radiation in certain directions.

11. In apparatus for signaling by means of electromagnetic waves, thecombination 'of an antenna with reflectors near to the antenna, thereflectors enclosing a space having a. natural frequency approximatelycoinciding with the frequency of the electromagnetic waves and means foradjusting the space enclosed by the reflectors so that it can be adaptedto different wave lengths.

RUDOLF' WEYRICH.

